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Plasma etching method

a technology of etching and plasma, applied in the field of plasma etching, can solve the problems of difficult to form an mtj device in a vertical shap

Active Publication Date: 2014-05-29
HITACHI HIGH-TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is a plasma etching method for making a magnetic film device in a vertical shape without affecting its quality. This method helps to create a vertically shaped MTJ device with high precision.

Problems solved by technology

However, the related art is based on the premise that a deposit is formed on the pattern side wall, meaning that the deposit on the pattern side wall makes it difficult to form an MTJ device in a vertical shape.

Method used

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first embodiment

[0026]First, FIG. 2A shows the film structure of the sample 12 used in the present invention. This is the sample 12 for forming an MTJ device. On a silicon substrate 18, the films are laminated from bottom to top in the following order: a Ta film 17 that is the bottom electrode, a CoFeB film 16 that is a fixed layer, an MgO film 15 that is a barrier layer, a CoFeB film 14 that is a variable layer, and a Ta film 13 that is the top electrode.

TABLE 1ProcessingSourceBias RFProcessingH2HeCH4pressureRF powerpowertimeStepml / minPaWWSecond180000.316004501152807730.31600200603807730.31600200120

[0027]With the Ta film 13 as the mask, etching is performed on the CoFeB film 14, MgO film 15, and CoFeB film 16 according to the condition shown in step 1 in Table 1. The condition is that the flow rate of N2 gas is 80 ml / min, the processing pressure is 0.3 Pa, the source RF power is 1600 W, the bias RF power is 450 W, and the processing time is 115 seconds. Then, the shape of the MTJ device is changed...

second embodiment

[0043]First, FIG. 6A shows the film structure of a sample 12 used in the present invention. This is the sample 12 for forming an MTJ device. On a silicon substrate 18, the films are laminated from bottom to top in the following order: a Ta film 17 that is the bottom electrode, a CoFeB film 16 that is a fixed layer, an MgO film 15 that is a barrier layer, a CoFeB film 14 that is a variable layer, and a Ta film 21 that is the top electrode. The Ta film 21 is half as thick as the Ta film 13 in the first embodiment.

TABLE 2ProcessingSource RFBias RFProcessingH2HeCH4pressurepowerpowertimeStepml / minPaWWSecond180000.316004501152807730.31600200303807730.31600200120

[0044]First, with the Ta film 21 as the mask, etching is performed on the CoFeB film 14, MgO film 15, and CoFeB film 16 according to the condition shown in step 1 in Table 2. The condition is that the flow rate of N2 gas is 80 ml / min, the processing pressure is 0.3 Pa, the source RF power is 1600 W, the bias RF power is 450 W, and ...

third embodiment

[0052]First, FIG. 7A shows the film structure of a sample 12 used in the present invention. This is the sample 12 for forming an MTJ device. On a silicon substrate 18, the films are laminated from bottom to top in the following order: a Ta film 17 that is the bottom electrode, a CoFeB film 16 that is a fixed layer, an MgO film 15 that is a barrier layer, a CoFeB film 14 that is a variable layer, and a Ta film 13 that is the top electrode.

TABLE 3ProcessingSource RFBias RFProcessingH2HeCH4pressurepowerpowertimeStepml / minPaWWSecond1807730.31600450125280000.31600200203807730.31600200120

[0053]First, with the Ta film 13 as the mask, etching is performed on the CoFeB film 14, MgO film 15, and CoFeB film 16 according to the condition shown in step 1 in Table 3. The condition is that the flow rate of N2 gas is 80 ml / min, the flow rate of He gas is 77 ml / min, the flow rate of CH4 gas is 3 ml / min, the processing pressure is 0.3 Pa, the source RF power is 1600 W, the bias RF power is 450 W, and...

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Abstract

A plasma etching method performs plasma etching on a sample, which has laminated films containing a variable layer of a magnetic film, a barrier layer of an insulating material, and a fixed layer of a magnetic film, using a hard mask, which includes at least one of a Ta film and a TiN film. The plasma etching method includes a first step of etching the laminated films using N2 gas; and a second step of etching the laminated films after the first step using mixed gas of N2 gas and gas containing carbon elements.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a plasma etching method, and more particularly to a plasma etching method for plasma etching a magnetic material.[0002]Today, development efforts are underway for a magnetoresistive random access memory (MRAM) in which data is stored in a magnetic tunnel junction (MTJ) device (hereinafter referred to as an MTJ device) by utilizing the giant magneto resistive (GMR) effect or the tunnel magneto-resistance (TMR) effect. An attempt is now made to form an MTJ device, which includes a magnetic material, by performing plasma etching.[0003]For example, JP-A-2005-314791 discloses a method in which high frequency is used to generate plasma from reaction gas, which contains hydrocarbon compound gas, gas of a compound having oxygen atom, and gas of a compound having nitrogen atom, and the metallic magnetic material film is etched using this plasma. This document also discloses that a fluorocarbon compound is used as the etching g...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11C11/02
CPCG11C11/02H10N50/01H01L21/3065
Inventor YOSHIDA, ATSUSHIYAMAMOTO, NAOHIROSUYAMA, MAKOTOYAMADA, KENTAROFUJITA, DAISUKE
Owner HITACHI HIGH-TECH CORP